Percussion fuse



March 25, 1941. M. BlRKlG-r YERCUSSION FUSE Filed oct. 21, 195s a W, n WW Patented Mar. 25, 1941 ,UNiTEo STATES Application October '21, 1938,Serial No. 236,366 In Belgium January 21, 1938 (Cl. lim-39) ence to theaccompanying drawing, given merely by way of example, and in which:

Fig. 1 is an axial sectional View of a percussion fuse made according toan embodiment of the invention;

Fig. 2 is a sectional view, corresponding to the same embodiment, butshowing the parts in different respective positions.

In the following description, it will be assumed that the invention isapplied to the production of a percussion fuse of the type abovementioned, for a shell of small caliber to be used in a firearm providedwith rif'ling.

The general structure of the fuse, excepting the percussion meansthereof, can be made of any suitable conventional manner, for instanceas illustrated by the drawing.

In this embodiment, the fuse includes a body 9 Claims.

The present invention relates to percussion fuses for projectilesrotating about their axes,

of the type in which the percussion system is.

` y temporarily locked in inoperative position by one or several pinsadapted to be moved out of lockingposition, so as to release thepercussion system, under the effect of the centrifugal accelerationresulting from the rotation of the projectile -about its axis. Theinvention is more especially, although not exclusively, concerned withpercussion fuses of this type for shells of small calibre.

In fuses of this type existing prior tov my invention, the locking pinsabove referred to were 1 driven off from the fuse body when thepercussion system was released.

Now, the pins thus driven off from the body Were moving at a very highspeed, which involved very serious drawbacks, especially when theprojectiles were utilized in firearms tted on aircraft, since, in thiscase, said pins could damage certain vital parts of said aircraft.

The chief object of -the present invention is to provide a fuse of thetype above referred to which is better adapted to meet the requirementsof practice and in particular which avoids the serious drawback abovementioned.

According to an essential feature of the present invention, thepercussion fuse includes at least one pin adapted temporarily to lockthe percussion system in inactive position, said pin lbeing adapted tobe moved out of locking position by the centrifugal accelerationresulting 3 from the rotation of the projectile around its axis, and arecess is provided for receiving said pin, at the time of the release ofthe percussion system, so that it cannot be driven out of the fuse.

40 According to another feature of the present invention, the pin inquestion serves to lock a striker which, together with said pin, iscarried by a movable support temporarily maintained in a position ofrest for which said pin and its recess or housing are not located inregister with each other, said support being adapted to occupy,

' under the influence of certain variations of the acceleration of theprojectile along its trajectory, an active position for which said pinand said recess or housing are located opposite each other.

Other features of the present invention will result from the followingdetailed description of some specific embodiments thereof.

Preferred embodiments of the present invention will be hereinafterdescribed, with referl on which is secured, by screwing, a cap 2, saidvECE body being adapted to fit into the mouth of the shell. through'themedium of a threaded ring 3. 'Ihis body l carries a sheath 4 inwhich adetonator is housed, said sheath being secured by screwing to the baseof ring 3.

A primercarrier 6 is provided with a flange caught between the fuse bodyI and said sheath 4.

The front part of the fuse is closed by means of a thin sheet or disc 1,which is, for instance, caught, along its periphery, between the body Iand the cap 2 of the fuse.

I will now describe the percussion system which constitutes the objectof the invention.

Advantageously, lthis percussion system includes, in the known manner, astriker 8, normally kept in inactive position by pins 9 or equivalentmeans (two such pins being used in the embodiment shown by the drawing)adapted to be moved away radially, so as to release said striker, underthe effect of the centrifugal acceleration resulting from the rotationof the pro- J'ectile about its axis.

According to the chief feature of the present invention, the device isarranged in such manner that pins 9 can be driven off .into recesses`Il) capable of preventing them from being expelled from the body of thefuse.

Such an arrangement therefore obviates any risk of accidents such asthose inherent in -the operation of fuses having locking pins which areexpelled from the fuse body.

l Preferably, according to a further feature of the present invention,these recesses are wholly closed at their end farthest from the axis ofthe fuse.

each of these recesses may be formed partly in the body I of the fuseand partly in its cap 2, by providing in these two last mentionedelements two radial holes, respectively, which open into an axial holeII forming a housing for striker 8. Each of these radial recesses has abottom I 0 against which the corresponding locking pin 9 is applied whenthe striker is released.

With such an arrangement, I prevent the possibility of destructiveagents leaking in into the body of the fuse, and in particular thepossibility of an inflow of water, which might damage the primer of saidfuse.

A fuse as above described further includes means for opposing prematurerelease of striker 8, that is to say for preventing the'fuse from actingat too short a distance fromA the gunVV v port I2 is adapted to occupy,under the effect of certain variations of the acceleration of theprojectile along its trajectory, an active position for which these pinsare located opposite their respective recesses, so that they can now bemoved r away radially under the effect of the centrifugal accelerationand release the striker.

Such an operation may, for instance, advantageously be obtained with thespecific arrangement shown by the drawing.

In this embodiment, in order temporarily to maintain support I2 in itsposition `of rest, I provide a locking means capable of releasing saidsupport under the effect of the centrifugal acceleration. This lockingmeans consists, for iny stance, of a split segment I3, interposedbetween the body I of the fuse and a shoulder I2 provided at the base ofthe sliding support I2.

The outer ends of pins 9 are made of frustoconical shape so that theycan already be partly engaged in recesses Ill when support I2 is inposition of rest.

The forces acting upon support I2 after a shot has been red, are thenthe following:

On the one hand, an axial force resulting from the inertia of saidsupport. The direction of this force changes at the same time as that ofthe acceleration of the projectile along its trajectory, that is to sayafter the projectile has left the firearm; and,

On the other hand, another axial force, directed toward the front end ofthe fuse, resulting from the reaction of the edges of recesses I0 uponthe frusto-conical ends of pins 9, which are urged lin the radialoutward direction by the centrifugal acceleration.

It will readily be understood that it is vpossible, by suitably choosingthe weights of support I2 and pins 9, and also the angle of theY cone ofthe latter, to obtain the result that the resultant of these forces isdirected toward the front end of the fuse, that is to say causes supportI2 to pass from its position of rest to its active position, only afterthe projectile has moved to a given distance from the muzzle of thefirearm. This distance, added to that corresponding tothe axial changeof position of support I2, determines the margin of safety.

In particular, in the case of shells of small calibre, it isparticularly advantageous to determine the weights above referred to insuch manner that this distance is equal to some meters.

rI'he fuse above described will operate in the following manner:

In position of rest, that is to say before the projectile is introducedinto the firearm, the various elements of the percussion systemrespectively occupy the positions of Fig. 1, support I2 being held inposition of rest by segment I3.

When the shot is red, the projectile starts rotating about its axis andsaid segment is moved away by the centrifugal force, thus releasingsupport I2, which however remains for a short time in position of restdue to the fact that the acceleration of the projectile along itstrajectory has an important positive value. When this value drops belowa certain value lower than that acting at the gun muzzle, said supportcomes into its active position and pins 9 are engaged into theirrecesses(position shown by Fig. 2). The fuse is now ready to operate. When theprojectile strikes an obstacle, cover disc 'I is broken andstriker 8driven in. The point of this striker now strikes the fuse primer, sothat said fuse now detonates.

Whatever be the embodiment that is chosen, the fuse according to thepresent invention has, in addition to the advantages above set forth,that of being of a simple construction, so that its cost of manufactureis relatively low and its operation is reliable.

In a general manner, while I have, in the above description, disclosedwhat I deem to be practical and efcient embodiments of the presentinvention, it should be well understood that I do noty wish to belimited thereto as there might be changes made in the arrangement,disposition, and form of the parts without departing from the principleof the present invention as comprehended within the scope of theappended claims.

What I claim is:

1. A percussion fuse of the type described which comprises, incombination, a frame, a support movable axially in said frame betweentwo extreme positions, a percussion device carried f support in aninoperative position, said locking member being movable radially awayfrom the axis of the fuse by centrifugal force to release saidpercussion device, at least one hole in said frame, said hole being solocated that said locking member is in register with said hole only whensaid support reaches its extreme position nearest the front of the fuse,and locking means for temporarily locking said support in its otherextreme position, said last means being brought out of action bycentrifugal force only, whereby said support can move towards the frontof the fuse only after the shot is fired.

2. A percussion fuse of the type described which comprises, incombination, a frame, a support movable axially in said frame betweentwo extreme positions, a striker carried by said support and movableaxially with respect thereto, at least one locking pin mounted in saidsupport normally locking said striker against movement with respect tosaid support in an inoperative position, said locking pin being movableradially away from the axis of the fuse by centrifugal force to releasesaid striker, at least one hole in said frame, said hole being solocated that said locking pin is in register with said hole only whensai-d support reaches its extreme position nearest the front of thefuse, and locking means for temporarily locking said support in itsother extreme position, said last means being brought out of action bycentrifugal force only, whereby said support can be moved towards thefront of the fuse only after the shot is fired,

3. A percussion fuse of the type described which comprises, incombination, a frame, a support movable axially in said frame betweentwo extreme positions, a percussion device carried by said support andmovable axially with respect thereto, at least one locking membermounted in said support normally locking said percussion device againstmovement with respect to said support in an inoperative position, saidlocking member being movable radially away from the axis of the fuse bycentrifugal force to release said percussion device, at least one holein said frame, said hole being so located that said locking member is inregister with said hole only when said support reaches its extremeposition nearest the front of the fuse, at least one abutment carried bysaid frame, at least one inclined surface on said locking member, saidabutment and inclined surface cooperating to produce by the centrifugalforce acting on said locking member a reaction parallel to the axis ofthe fuse tending to move said support towards its extreme positionnearest the front of the fuse, and locking means for temporarily lockingsaid support in its other extreme position, said means being brought outof action by centrifugal force only, whereby said support can be movedtowards the front of the fuse only after the shot is red.

4. A percussion fuse of the type described which comprises, incombination, a frame, a support movable axially in said frame betweentwo extreme positions, a striker carried by said support and movableaxially with respect thereto, at least one locking pin mounted in saidsupport normally locking said striker against movement with respect tosaid support in an inoperative position, said locking member beingmovable radially away from the axis of the fuse by centrifugal force torelease said striker, at least one hole in said frame, said hole beingso located that said locking pin is in register with said hole only whensaid support reaches its extreme position nearest the front of the fuse,at least one inclined surface on said locking pin, at least one abutmentcarried by said frame, said abutment and inclined surface cooperating toproduce by the centrifugal force acting on said locking pin a reactionparallel to the axis of the fuse tending to move said support towardsits extreme position nearest the front of the fuse,and locking means fortemporarily locking said support in its other extreme position, saidmeans being brought out of action by centrifugal force only, wherebysaid support can be moved towards the front of the fuse only after theshot is fired.

5. A percussion fuse according to claim 2 in which the outer end of saidpin is of frusto-conical shape, and said locking means normally locksaid support in such an axial position that said frusto-conical end isengaged at an intermediate point along its conical surface with the edgeof said hole, whereby the centrifugal force acting upon said pin afterthe fuse has started rotating about its axis tends by reaction on theedge of said hole of said frusto-conical end to urge said supporttowards the front of the fuse.

6. A percussion fuse according to claim 1 in which the locking means ofthe support comprise a split segment interposed between said support andsaid frame and capable of being forced open by centrifugal force.

7. A percussion fuse according to claim 2 in which the locking means ofthe support comprise o a split segment interposed between said supportand said frame and capable of being forced open by centrifugal force.

8. A percussion fuse according to claim 2 in which the locking means ofthe support comprise a split segment interposed between said support andsaid frame and capable of being forced open by centrifugal force and inwhich the outer end of said pin is of frusto-conical shape, and saidlocking means normally lock said support in such Y an axial positionthat said frusto-conical end is engaged at an intermediate point alongits conical surface with the edge of said hole, whereby the centrifugalforce acting upon said pin after the fuse has started rotating about itsaxis tends by reaction on the edge of said hole of said frustoconicalend to urge said support towards the front of the fuse.

9. In a percussion fuse according to claim 1, sai-d frame having arecess therein, said support having a flange thereon within said recess,and said locking means comprising a split elastic ringnormallypositioned between said flange and the bottom of said recess.

MARC BIRKIGT.

